In the operation of pay telephones, it is important to be able to temporarily accept a coin pending the connection of the attempted telephone call. For example, if the telephone call is not completed, the coins are to be refunded. On the other hand, if the call does go through and is answered on the other end, the coins are accepted and passed to the coin receptacle or coin box.
An early example of a coin escrow mechanism is shown in U.S. Pat. No. 751,081 of Larned (patented in 1904). The '081 patent describes a coin-controlled telephone apparatus in which coins are deposited and either initially rejected along a coin return path or selectively captured temporarily subject to permanent collection upon the connection of the telephone call. The '081 patent describes the use of a tilting plate arranged vertically alongside a vertical coin path and that the tilting plate includes a number of control pins. The tilting action of the tilting plate selectively moves one or more of these control pins into and out of the coin path to effectively direct coins one way or another or to temporarily hold coins to determine whether to return the coin or to pass the coin to a coin collection chamber. The '081 patent describes that the control of the tilting plate is effected by a remote telephone operator at a central switchboard.
U.S. Pat. No. 886,499 of J. Harrison discloses a pay telephone box with a coin acceptance mechanism using a V-shaped gate pivotally mounted in the coin chute at a point where the chute branches into a depositing chute and a return chute. As in the Larned patent, the '499 patent describes control by a remote operator who activates an actuator in the mechanism which deposits the coin into either of the desired chutes.
U.S. Pat. No. 1,098,673 of Lyng discloses a coin collector or coin escrow mechanism which uses a pivotal coin escrow door positioned beneath a coin hopper. The coin escrow door is supported by a pendulum arm which is pivoted from a position above the door. The pendulum arm has a roller at the bottom thereof for engaging a curved cam beneath the lower door and as the arm swings the roller in one direction, the lower door is allowed to tilt downwardly in an opposite direction. However, because the pendulum arm moves upwardly somewhat as it swings sideways, it tends to continue to hold the escrow door tightly closed until a substantial angular movement of the pendulum arm has been effected. Indeed, the curved cam of Lyng appears to have a radius of curvature closely matching the curvature of the pivotal motion of the roller about the pivot point of the pendulum arm, thereby maintaining a consistent upward force on the lower door until the pendulum arm is rotated enough to move the roller from between the pivot points about which the lower door is supposed to rotate. This requires that the pendulum arm be moved a substantial amount in order to release the coins from the hopper into one chute or the other. In fact, to ensure that the lower door eventually opens, a reverse bend is formed in the cam beyond the pivot points to force the door open once the roller has cleared the pivot points. Requiring such an exaggerated motion tends to require substantial power to actuate the mechanism.
More recently, U.S. Pat. No. 4,630,624 of Turner discloses an escrow apparatus including a pair of interleaved door panels disposed at an angular orientation with respect to each other and which are each pivotally moveable between a pair of fixed boundaries. The panels are selectively pivotable to allow coins held in the chamber to move either to an acceptance chute or to a return chute.
U.S. Pat. No. 4,782,937 of Chen. et al. relates to a coin escrow device consisting of a housing and a pair of interleaved gates for selectively discharging coins to a return chute or an acceptance chute. For operating the gates, solenoids are provided, which solenoids act through a linkage mechanism for moving the gates.
U.S. Pat. No. 5,216,707 discloses a coin escrow unit which operates on the principles of a relay. The relay is designed to trip one way or another based on receiving a signal of positive 130 volts DC or negative 130 volts DC and based on there being a certain amount of current flowing. Thus, in order to trip the relay one way or the other, both a current criteria and a voltage criteria are to be met. In order to ensure that the relay trips one way or the other only when desired (and not when a simple coin test is being conducted to see if a coin has been received or not) mechanical adjustments of springs and tension on the springs must be made in the field to compensate for local conditions. This makes the manufacturing of a uniformly performing product extremely problematical and requires careful installation and frequent maintenance of the relay in order to ensure proper operation.
While there are various mechanisms known in the prior art for providing a coin escrow mechanism, in general the known mechanisms tend to suffer from reliability problems, high power requirements, a tendency to self-actuate as a result of the accumulated weight of coins in the coin hopper, and to be somewhat susceptible to jamming. Also, the known arrangements tend to be somewhat mechanically complex and require field adjustments. Accordingly, a need yet remains for a coin escrow apparatus which is mechanically simple, reliable, doesn't need to be adjusted in the field, has low power requirements, resists self-actuation, and resists jamming. It is to the provision of such a coin escrow apparatus that the present invention is primarily directed.